In liquid heating systems, a metallic container such as a boiler or tank is used to store the liquid and the boiler or tank is heated to raise the temperature of the liquid. Corrosion in such liquid heating systems is a major disruptive factor. Typically, the metallic container is made of less reactive metals which have less free electrons to participate in oxidation process, thus delaying the corrosion of the metallic containers to an extent. Further, the inner surface of hot water tanks may be coated with glass or ceramic to overcome corrosion. However, to further delay the rate at which the metal containers corrode, a technique referred to as electrochemical process is used. An electrochemical process generally, refers to provisioning an anode within the metallic container. Typically, the metals used for making anodes are highly reactive compared to the metals used for making the containers. Highly reactive metals used in making anodes have more electrons available for oxidation. As a result, the anodes corrode quickly resulting in further delaying of the oxidation of the metallic container, which acts as a cathode. Anode is used for protecting a cathode as the anode further delays corrosion of cathode (metallic container).
Anode is a metallic rod, which is used in cathodic protection, where it corrodes to protect the metallic container (i.e., cathode). Usually, highly reactive metals like aluminum, magnesium, zinc, or any alloy, which are more reactive than the cathode is used as an anode. The metallic containers are generally made of less reactive metals such as steel, copper and its alloys.
In many scenarios, the liquid used in the liquid heating system may include hard water, which may comprise high amounts of dissolved minerals. While the hard water is heated, some of these dissolved minerals may precipitate on the inner surface of metallic container to form a hard layer rigidly attached to the inner surface of the metallic container. The hard layer may decrease the transfer of heat and increase the amount of heat required to raise the temperature of the liquid to a preset level. Such hard layer formation may reduce the efficiency of the liquid heating system. Also, the hard layer may corrode the inner surface of the metallic container.
Anodes are generally provided in the form of rods and the rods are fitted into the metallic container. For example, the anode rod is secured tightly to the lid of the metallic container. The top end of the anode rod is provided with external threads and the lid is provided with the internal threads to fix the anode rod firmly to the lid. The anode rods corrode at a much faster rate to further delay the corrosion of the metallic container and the anode rods are to be replaced more frequently compare to the metallic container. Unfortunately, the external threads provisioned on the top end of the anode rod may also get corroded. The liquid heating system has to be halted before replacing the anode rods at frequent intervals. In residential setup, the service cost to replace the anode may be high and mostly the anode rods may not replaced, which is the major cause for liquid heater tank failures. Halting the liquid heating systems may cause downtime in an industrial setup, disrupting the operations of the industry, which may lead to decreased productivity and sub optimal use of resources. Another challenge is that of removing such anode rods without damaging the internal threads of the lid as the external threads on the top end of the anode rod are corroded.